Howdy.
First you need to get your mind around the fact that what you (and almost everyone else) call an "AK-47" is more than likely an AKM (AK modernized). The AK-47 has not been produced very much at all since 1959 (the year the AKM was introduced).
The AK-47 is not very compatible at all with the AKM/AK74/AK100 series of rifle (basically, only the magazines and a few internal parts interchange)
The AKM/AK74 and AK100, on the other hand, have about 90% parts commonality (including your hand guards).